mem: Remove array_size dependency

The mem module declares array_size as a test dependency, and includes it in
test/api.c, but doesn't actually use it.  This removes the unneeded
dependency.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

ccan/mem/_info

@@ -23,7 +23,6 @@ int main(int argc, char *argv[])
 	}
 
 	if (strcmp(argv[1], "testdepends") == 0) {
-		printf("ccan/array_size");
 		return 0;
 	}
 

ccan/mem/test/api.c

-#include <ccan/array_size/array_size.h>
 #include <ccan/mem/mem.h>
 #include <ccan/tap/tap.h>